IS432 Semi-Structured Data Lecture 5: XSLT Dr. Gamal Al-Shorbagy.

IS432Semi-Structured Data

Lecture 5:

XSLT

Dr. Gamal Al-Shorbagy

XML Stylesheet Langugae

Extensible Stylesheet Language (XSL) Language for document transformation

Transformation Converting XML to another form

Formatting objectsLayout of XML document

Search document contents Navigating XML document tree nodes

http://www.codeproject.com/Articles/294380/Applying-XSLT-Stylesheet-to-an-XML-File-at-Runtime



XML Stylesheet Language

XSL-FO

XSLT

XPathNavigating XML Document Formatting XML Document

Transforming XML Document

CSS (Cascading Style Sheets)

• CSS = Style Sheets for HTML• HTML uses predefined tags, and the meaning

of each tag is well understood.• The <table> tag in HTML defines a table - and

a browser knows how to display it.• Adding styles to HTML elements are simple.

Telling a browser to display an element in a special font or color, is easy with CSS.

XML Style Sheets

• XSL = Style Sheets for XML• XML does not use predefined tags (we can use

any tag-names we like), and therefore the meaning of each tag is not well understood.

• A< table> tag could mean an HTML table, a piece of furniture, or something else - and a browser does not know how to display it.

• XSL describes how the XML document should be displayed!

XSL In Parts

• XSL - More Than a Style Sheet Language• XSL consists of three parts:– XSLT - a language for transforming XML

documents– XPath - a language for navigating in XML

documents– XSL-FO - a language for formatting XML

documents

What is XSLT?

• XSLT stands for XSL Transformations• XSLT is the most important part of XSL– XSLT transforms an XML document into another

XML document– XSLT uses XPath to navigate in XML documents– XSLT is a W3C Recommendation

XSLT = XSL Transformations

• XSLT is the most important part of XSL.• XSLT is used to transform an XML document

into another XML document– Or another type of document that is recognized by

a browser, like HTML and XHTML. – Normally XSLT does this by transforming each XML

element into an (X)HTML element.

XSLT = XSL Transformations

• With XSLT you can add/remove elements and attributes to or from the output file. – You can also rearrange and sort elements, – Perform tests and make decisions about which

elements to hide and display, and a lot more.

• A common way to describe the transformation process is to say that XSLT transforms an XML source-tree into an XML result-tree.

Browsers Support for XSLT• Mozilla Firefox

– Firefox supports XML, XSLT, and XPath from version 3.• Internet Explorer

– Internet Explorer supports XML, XSLT, and XPath from version 6.– Internet Explorer 5 is NOT compatible with the official W3C XSL

Recommendation.• Google Chrome

– Chrome supports XML, XSLT, and XPath from version 1.• Opera

– Opera supports XML, XSLT, and XPath from version 9. Opera 8 supports only XML + CSS.

• Apple Safari– Safari supports XML and XSLT from version 3.

Example Study

• How to transform XML into XHTML using XSLT.

Transform XML into XHTML

1. Style Sheet Declaration2. Start with a Raw XML Document3. Create an XSL Style Sheet4. Link the XSL Style Sheet to the XML Document

Style Sheet Declaration

<xsl:transform version="1.0“ xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:stylesheet version="1.0“ xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

W3C XSLT Recommendation

The official W3C XSLT namespaceMust attribute, value pair

top

Raw XML Document<?xml version="1.0" encoding="ISO-8859-1"?>

< catalog><cd>

<title>Empire Burlesque</title><artist>Bob Dylan</artist><country>USA</country><company>Columbia</company><price>10.90</price><year>1985</year>

</cd>..

< /catalog>

An XSL Style Sheet<?xml version="1.0" encoding="ISO-8859-1"?>

< xsl:stylesheet version="1.0“ xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

< xsl:template match="/"> <html> <body>

<h2>My CD Collection</h2><table border="1">

<tr bgcolor="#9acd32"><th>Title</th><th>Artist</th>

</tr><xsl:for-each select="catalog/cd">

<tr><td><xsl:value-of select="title"/></td><td><xsl:value-of select="artist"/></td>

</tr></xsl:for-each>

</table> </body> </html> < /xsl:template>

< /xsl:stylesheet>

XML document declaration

This document is a Stylesheet

Linking XML with Stylesheet<?xml version="1.0" encoding="ISO-8859-1"?><?xml-stylesheet type="text/xsl" href="cdcatalog.xsl"?>< catalog>

<cd><title>Empire Burlesque</title><artist>Bob Dylan</artist><country>USA</country><company>Columbia</company><price>10.90</price><year>1985</year>

</cd>..

< /catalog>

XSL Templates

• An XSL style sheet consists of one or more set of rules that are called templates.

• A template contains rules to apply when a specified node is matched.

XSL Templates

• The <xsl:template> Element– Used to build templates

• The match attribute – Associates a template with an XML element.– Also used to define a template for the entire XML

document. – The value of the match attribute is an XPath

expression • (i.e. match="/" defines the whole document).

XSL Templates

• The <xsl:template> element defines a template.

• The match="/" attribute associates the template with the root of the XML source document.

• The content inside the <xsl:template> element defines some HTML to write to the output.

Xpath ExpressionsPath Expression Result

bookstore

/bookstore

bookstore/book

//book

bookstore//book

//@lang

<?xml version="1.0" encoding="ISO-8859-1"?><bookstore> <book> <title lang="eng">Harry Potter</title> <price>29.99</price> </book> <book> <title lang="eng“>XML 4 Dummies</title> <price>39.95</price> </book> <book> <title lang=“kor“>The Han River</title> <price>149.95</price> </book></bookstore>

Example XSL Style Sheet<?xml version="1.0" encoding="ISO-8859-1"?>






<tr><td>.</td><td>.</td>



< /xsl:stylesheet>



End of templateEnd of stylesheet

associates the template with the root of the XML source document

HTML to write to the output

Output

Stylesheet Nuts&Bolts

• The <xsl:value-of> Element–Extract the value of an XML element and

add it to the output stream of the transformation–The select attribute contains an XPath

expression

<tr> <td><xsl:value-of select="catalog/cd/title"/></td> <td><xsl:value-of select="catalog/cd/artist"/></td> </tr>







<tr><td><xsl:value-of select="catalog/cd/title"/></td><td><xsl:value-of select="catalog/cd/artist"/></td>



< /xsl:stylesheet>




Selecting a specific element value


Output


• The <xsl:for-each> Element– select every XML element of a specified element

list– Note: An XPath expression in value of select.

<xsl:for-each select="catalog/cd"><tr>

<td><xsl:value-of select="title"/></td><td><xsl:value-of select="artist"/></td>











< /xsl:stylesheet>




Selecting each element in a list of elements


Output

Filtering the Output using PredicatesPath Expression Result/bookstore/book[1]

/bookstore/book[last()]

/bookstore/book[last()-1]

/bookstore/book[position()<3]

//title[@lang]

//title[@lang=‘kor']

/bookstore/book[price>35.00]

/bookstore/book[price>35.00]/title

<?xml version="1.0" encoding="ISO-8859-1"?><bookstore> <book> <title lang="eng">Harry Potter</title> <price>29.99</price> </book> <book> <title lang="eng“>XML 4 Dummies</title> <price>39.95</price> </book> <book> <title lang=“kor“>The Han River</title> <price>149.95</price> </book></bookstore>






</tr><xsl:for-each select=“catalog/cd[artist='Bob Dylan']“ >




< /xsl:stylesheet>




Filtering output


Output ?


• The <xsl:sort> Element– Sort the out put wrt select value– Value of select is ?.

<xsl:for-each select="catalog/cd"><xsl:sort select="artist"/><tr>








</tr><xsl:for-each select=“catalog/cd“ >

<xsl:sort select="artist"/> <tr>




< /xsl:stylesheet>




Sorting output


Output


• Placement: The <xsl:if> element always inside the <xsl:for-each> element

• Attribute: The Value of test is an XPath expression.

<xsl:for-each select="catalog/cd"> <xsl:if test="price > 10"> <tr> <td><xsl:value-of select="title"/></td> <td><xsl:value-of select="artist"/></td> </tr> </xsl:if> </xsl:for-each>

Example XSL Style Sheet<?xml version="1.0" encoding="ISO-8859-1"?>< xsl:stylesheet version="1.0“ xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> < xsl:template match="/"> <html> <body>


<tr bgcolor="#9acd32"><th>Title</th> <th>Artist</th> <th>Price</th>

</tr>

<xsl:for-each select=“catalog/cd“ > <xsl:if test=“price > 10”>

<tr><td><xsl:value-of select="title"/></td><td><xsl:value-of select="artist"/></td><td><xsl:value-of select=“price"/></td>

</tr> <xsl:if />

</xsl:for-each></table>

</body> </html> < /xsl:template>< /xsl:stylesheet>

predicate


Output


• The <xsl:choose>, <xsl:when>, and <xsl:otherwise>– a multiple conditional test against the XML file, add

<xsl:choose> <xsl:when test="expression"> ... some output ... </xsl:when> <xsl:otherwise> ... some output .... </xsl:otherwise></xsl:choose>

Stylesheet Nuts&Bolts <xsl:for-each select="catalog/cd"> <tr> <td><xsl:value-of select="title"/></td> <xsl:choose> <xsl:when test="price > 10"> <td bgcolor="#ff00ff"> <xsl:value-of select="artist"/></td> </xsl:when> <xsl:otherwise> <td><xsl:value-of select="artist"/></td> </xsl:otherwise> </xsl:choose> </tr> </xsl:for-each>

Output

<xsl:apply-templates><xsl:template match="/"> <html> <body> <h2>My CD Collection</h2> <xsl:apply-templates/> </body> </html></xsl:template>

<xsl:template match="cd"> <p> <xsl:apply-templates select="title"/> <xsl:apply-templates select="artist"/> </p></xsl:template> <xsl:template match="title">

Title: <span style="color:#ff0000"> <xsl:value-of select="."/></span> <br /></xsl:template>

<xsl:template match="artist"> Artist: <span style="color:#00ff00"> <xsl:value-of select="."/></span> <br /></xsl:template>

Output

References

• W3 Schools– http://www.w3schools.com/

• Online XSLT Test Tool– http://xslttest.appspot.com/

http://xslttest.appspot.com/



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IS432 Semi-Structured Data Lecture 5: XSLT Dr. Gamal Al-Shorbagy.

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